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The effect of hydroxyapatite coating on ingrowth of bone into cavities in an implant
Abstract
A canine implant study was performed to assess whether hydroxyapatite (HA) could induce bone to close gaps at the bone-prosthesis junction. Titanium alloy (TiAlV) plates with varying grooves cut into them (1, 2, and 3 mm deep) and identical on both sides were sprayed on one side with HA and left as bare metal on the other. These were then implanted into the distal femora of dogs that were killed 4 and 8 weeks afterwards. Specimens were analyzed using optical microscopy and microradiography. Results show that the presence of HA induces bone to grow almost completely down the deepest groove by 8 weeks. In the 1- and 2-mm grooves at 4 weeks the depth of penetration of bone into the grooves was greater on the HA coated side (but the actual volume of bone in the grooves was greater on the TiAlV side because the bone present was more dense). We conclude that the presence of HA induces bone to close relatively large gaps. Although bone does not grow all the way into uncoated defects there can be more bone here in the short term. This feature of HA may be of great value in hip implant fixation.
... The femoral component of the prosthesis (C2F Implants) was cobalt-chromium material. Models of cementless prosthesis that offer initial stability and favor instant osteointegration are provided for right and left knees, in available sizes, twice covered with stratums of high porosity titanium and hydroxyapatite plasma sprayed (13)(14)(15)(16)(17). ...
... Physiological kinematics replicates natural femoral roll-back and allows deep flexion occurrence. The tibial component is also cobalt-chromium tibial tray 5 sizes available in uncemented version covered twice with stratums of high porosity titanium and hydroxyapatite plasma sprayed (17)(18)(19), which offers initial stability and favors instant osteointegration (20). The tibial tray, that is anatomically configured, matches each of the two knees (right and left). ...
... The clinical characteristics of the patients, hip knee arthroplasty angle pre-operator (varus or valgus), etiology, and surgical approach are summarized in Table II. Hydroxyapatite coating (10,14,(16)(17)(18) acts by providing anchorage between the implant and the bony surface. The ability of the bone to adapt and connect to the hydroxyapatite layer of knee implants favors reliable osteointegration and the long-term survival of the implant. ...
Osteoarthritis is mainly located in the knee area. It is an important concern related to the population health, determined by the influence on the quality of life of patients. Total knee arthroplasty (TKA) with uncemented fixation is among the most encountered procedures performed in patients of a younger age. The present study investigated the response of patients (quality of life, mobility and pain management) with titanium/hydroxyapatite-coated implants with polyethylene inserts. A total of 57 patients with knee arthroplasty were studied with an average age of 54.1±4.9 years and 57.8% were females. The present study focused on the following aspects: The components of such a prosthesis and the way they contribute to a physiological fixation/recovery; how the implant surgery is performed; the clinical and demographic characteristics of the patients; postoperative pain assessment in different types of movement; the management of the movement capacity 1 year after the surgery; and complications that may occur. One year after the surgery, these patients reported pain release, considerably favorable results in everyday activities , and good mobility (capable of using the car, rising from the bed or standing). Knowledge and accurate observation of the correct steps in performing this surgery and the role of the components of the prosthesis can lead to favorable therapeutic outcomes for patients with knee osteoarthritis.
... In 1987 and 1988 hydroxyapatite (HA)-coated prostheses became available after experimental studies had shown that this coating gave more complete bone apposition to ridged implants than to smooth shot-blasted surfaces. 4 A proximally HA-coated version of the RPF (RPF+HA; Fig. 3) was introduced in 1988 and used when available in parallel with the uncoated RPF until late 1989. Clinical migration measurements then showed that the RPF+HA gave significantly more early stability than the RPF, 5 and use of this latter prosthesis ceased. ...
... The characteristics of the coat are a relative crystallinity of 70% to 90%, a thickness of 55 to 90 m, a bond shear strength of 25 MPa minimum, purity of 97% to 98% and roughness of 6 to 16 mRa. The biological effects of this HA coat on bone conduction have been reported by Stephenson et al, 4 and we have studied its effect upon early 5 and later 16 migration of the prosthesis. ...
We compared the radiological appearances and survival of four methods of fixation of a femoral stem in 538 hips after follow-up for five or ten years. The fixation groups were: 1) press-fit shot-blasted smooth Ti-Al-V stem; 2) press-fit shot-blasted proximally ridged stem; 3) proximal hydroxyapatite (HA) coating; and 4) cementing.
Survival analysis at five to ten years showed better results in the HA-coated (100% at five to six years) and cemented stems (100% at 5 to 6 years) than in the two press-fit groups. There was a higher mean rate of migration in the smooth and ridged Ti-Al-V shot-blasted press-fit groups (0.8 mm/year and 0.6 mm/year, respectively) when compared with the HA-coated and cemented prostheses (both 0.3 mm/year). More radiolucent lines and osteolytic lesions were seen in the press-fit groups than in either the HA-coated or cemented implants, with a trend for a lower incidence of both in the HA compared with the cemented group. Proximal osteopenia increased in the press-fit and cemented prostheses with time, but did not do so in the HA group. There was a higher incidence of resorption of the femoral neck with time in the cemented group than in the other three.
We conclude that the HA and the cemented interfaces both provide secure fixation with a trend in favour of HA. The cemented prosthesis meets the suggested National Institutes of Health definition of ‘efficacious’ at ten years.
... Hydroxyapatite [Ca10(PO4)6(OH)2], (HAP), has been widely used in dental and orthopedic implants, due to its chemical and crystallographic similarity with bone minerals [1][2][3]. ...
... To further optimize the process based on the regression equations (Eq(s). [3][4][5]; experiments were conducted as proposed by the steepest method. The regression coefficient of standoff Distance (X1) in Eq. 4 was chosen as a standard because its coefficient is higher among the other coefficients in Eq(s). ...
In this work, sequential optimization strategy based statistical design was employed to enhance the mechanical properties of hydroxyapatite coatings onto a pure magnesium substrate using a cold spray technique. A fractional factorial design (24-1) was applied to elucidate the process parameters that significantly affected the mechanical properties of the coating samples. Standoff distance, surface roughness, and substrate heating temperature were identified as important process parameters affecting thickness, nanohardness, and the elastic modulus of the coating sample. The overlaid method analysis was employed to determine tradeoff optimal values from multiple regressive equations. Then, finally, steepest method analysis was used to reconfirm and relocate the optimal domain from which the factor levels for maximum mechanical properties of the coating were determined at 49.77mm standoff distance, 926.4grit surface roughness, and 456°C substrate heating temperature, which can accommodate the optimum requirements for the cold spray process with a coating of 49.77μm thickness, 462.61MPa nanohardness, and 45.69GPa elastic modulus. Scanning electron microscopy revealed that a short standoff distance, high surface roughness, and high substrate temperatures improved the bond between the coated layers and substrates.
... The degree of adhesion and disposition of these cells determine their ability to proliferate and differentiate into osteoblasts upon contact with the implant. The latter is crucial in the development of a mechanically strong interface of complete fusion between the implant surface and bone tissue without a layer of fibrous tissue [29][30][31][32][33]. ...
Introduction Technological advances in bone tissue engineering have improved orthopaedic implants and surgical techniques for bone reconstruction. This approach allows overcoming inconvenience of the paucity of autologous materials available and donor site morbidity.
Aim To demonstrate advances of the past 30 years in the development of bioimplants providing alternatives to bone grafting in reconstructive orthopaedics.
Methods Preparing the review, the scientific platforms such as PubMed, Scopus, ResearchGate, RSCI were used for information searching. Search words or word combinations were bioactive osteoinductive implants, bone grafting, bone reconstruction, hydroxyapatite, bone scaffolds.
Results The main trends in tissue engineering in the field of orthopaedics are represented by construction of three-dimensional structure implants guiding cell migration, proliferation and differentiation as well as mechanical support. Association with bone morphogenetic proteins, growth factors enables proliferation and differentiation of cell types of the targeted bone tissue. A promising advancement should be biodegradability with a controllable degradation rate to compliment cell/tissue in-growth and maturation in limb reconstruction.
Discussion This review presents and discusses the experimental and clinical application of biotolerant, bioinert and bioactive materials for reconstructive bone surgery. Future generations of biomaterials are designed to be osteoconductive and osteoinductive.
Conclusion Properties of polycaprolactone (PCL) filled with hydroxyapatite (from 10 to 50 wt %) make this hybrid material with controllable absorption a promising strategy for reconstructive surgery in comparison to other materials.
... Summarizing the available information on the biomechanical and biomedical properties of CaPO4-deposited implants, the following data can be claimed. Compared to uncoated controls, deposited CaPO4 improved bone-implant contact [639,964,965,[1037][1038][1039][1040][1041][1042][1043], initial stability [1044], implant fixation [910,[1045][1046][1047][1048][1049] and nanomechanical properties of adjacent bone [1050], higher torque values [1038,1039,1049,1051] and extrusion strength [1052], protecting the interface from wear particles [1053], closing small gaps [1054,1055], reducing ion emissions from metal substrate [963,[1056][1057][1058], retarding metal degradation and corrosion [38,43,78,79,465,941,[1059][1060][1061], bone growth [1062][1063][1064], remodeling [1065,1066], osteointegration [35,486,914,[1067][1068][1069][1070], improving biocompatibility [1071], osteoconductivity [465,639,782,997,1004,[1072][1073][1074][1075], osteoinductivity [1076], bone immunomodulation [1077], osteogenesis [160, 1042,1049,1078,1079], early bone [486,1048,[1079][1080][1081] and healing [1082] responses, prevention of fibrous tissue formation ( Figure 40) [180,1083], ectopic bone formation [507], osteoblast density [1084] and osteoblast proliferation [759], and improvement of the clinical performance of orthopedic hips. Furthermore, the antimicrobial properties of deposited CaPO4 have been detected in several studies [38,1084]. ...
The present overview describes various production techniques for biocompatible calcium orthophosphate (abbreviated as CaPO4) deposits (coatings, films and layers) on the surfaces of various types of substrates to impart the biocompatible properties for artificial bone grafts. Since, after being implanted, the grafts always interact with the surrounding biological tissues at the interfaces, their surface properties are considered critical to clinical success. Due to the limited number of materials that can be tolerated in vivo, a new specialty of surface engineering has been developed to desirably modify any unacceptable material surface characteristics while maintaining the useful bulk performance. In 1975, the development of this approach led to the emergence of a special class of artificial bone grafts, in which various mechanically stable (and thus suitable for load-bearing applications) implantable biomaterials and artificial devices were coated with CaPO4. Since then, more than 7500 papers have been published on this subject and more than 500 new publications are added annually. In this review, a comprehensive analysis of the available literature has been performed with the main goal of finding as many deposition techniques as possible and more than 60 methods (double that if all known modifications are counted) for producing CaPO4 deposits on various substrates have been systematically described. Thus, besides the introduction, general knowledge and terminology, this review consists of two unequal parts. The first (bigger) part is a comprehensive summary of the known CaPO4 deposition techniques both currently used and dis-continued/underdeveloped ones with brief descriptions of their major physical and chemical principles coupled with the key process parameters (when possible) to inform readers of their existence and remind them of the unused ones. The second (smaller) part includes fleeting essays on the most important properties and current biomedical applications of the CaPO4 deposits with an indication of possible future developments.
... Choudhuri et al. [83] investigated the bio-ceramic deposit (HAP and Ti) for various purposes of medical implants and dental to improve bone amalgamation. Several investigations were carried out on HAP deposit (Ca 10 (PO 4 ) 6 (OH) 2 for various medical surgical applications since HAP deposit delivers same crystallised and chemicalised properties as that of skelet mineral [84][85][86]. Cinca et al. [87] investigated the coating properties of bioactive HAP, CS deposit on Ti-6Al-4V and Al7075T6 base material. As a result that coated specimen is less expensive for biomedical purpose, yet it is ductile in nature. ...
Cold spray process (CSP) is a thermal spray technology in which coating (10–40 µm) is formed in the solid state by the impingement of power particles with supersonic velocity (200–1,200 m/s2) on coupon employing compressed gas jet, below the melting point of coating powder. It is commonly referred as cold gas dynamic spray, high velocity powder deposition, kinetic spray and kinetic energy metallisation process. Using CSP, various engineering materials (metals, polymers and ceramics) and its composites can be deposited. It is unique and promising approach for obtaining surface coating and offers various technological benefits over thermal spray as kinetic energy is employed for deposition rather than thermal energy. This offers great benefits in additive manufacturing (AM) to develop a component denser, low oxide coating free of tensile residual stresses, and undesired chemical reactions compared to conventional AM and coating techniques. Cold spray additive manufacturing (CSAM) is the powerful and emerging technique in the field of AM to develop engineering components with improved performance covering broad range of functionalities of surface, subsurface and interfaces. There are few flaws in this technique; however, extensive research work is going in CSAM and repairing of components to meet the real-time applications. The main objective of this review article is to summarise the history, effect of process parameters on surface coating, research and development in CSP along with its implementation in AM, component repairing and biomedical, antimicrobial and electrical applications. A discussion on future trends in CSAM is also provided at the end part of this article.
... The experimental outcome indicates that an adequate clinical primary femoral stability is most likely achieved by the newer Attune PS system as well. Important sidenote, however, are that both PS systems use a different surface coating, which may affect primary stability [8], and the Triathlon device contains hydroxyapatite, which may lead to further differences in bone ingrowth and related long-term fixation [27]. ...
Sufficient primary stability through interference fit is required for bone ingrowth and subsequent long-term fixation of cementless knee replacement implants, and can be evaluated in experimental testing. In this study, primary stability of a novel posterior-stabilized (PS) femoral component (Attune PS) and a contemporary PS component (Triathlon PS) were analyzed, and compared to previous outcomes of cruciate-retaining (CR) implants. Potential bone ingrowth was evaluated by measuring micromotions over the implant−bone interface in six cadaveric femur pairs under two loading conditions using digital image correlation, for a paired comparison of the PS implants. Push-off forces required to achieve implant removal under high-flexion were determined as a measure of implant fixation. Achieved interference fit was determined by reconstructing the implant positions through use of separate implant and resected bone geometries. Lower overall micromotions and a higher average push-off force were measured in the Attune PS implant, indicating increased initial fixation compared to the Triathlon PS design. Interference fit was significantly higher for the Attune PS and was related to lower gait micromotions in Triathlon and overall PS groups. Based on reported clinical results and the comparison with available CR implant results, both PS implants are expected to provide sufficient initial clinical stability.
... There are no bioactive metals that would accelerate reparative osteogenesis. In orthopedics, chromiumnickel and chromium-nickel-molybdenum corrosionresistant steels, alloys of cobalt, tantalum, titanium, pure metals -nickel, silver, titanium are most often used for the manufacture of surgical implants [10]. ...
The article reports on the results of surgical treatment in 20 patients with bone tumors using a coating containing bioactive glass on the contact surface of the fixation plate. As a result of metallic osteosynthesis of the bones, infectious complications were observed in 1 (5%) patient and tumor recurrence was observed in 2 (10%) patients. Limb function after metallic osteosynthesis ranged from 72.3% to 97.4% depending on the location of the lesion focus. The quality of life of the operated patients increased to 75–85 points. Thus, the use of plates with bioactive glassbased material deposited on the contact surface of the plate, in metallic osteosynthesis for pathological bone fracture or at the risk of pathological bone fracture achieves more effective integration of metal plate with bone. Consequently, a better functional stability of the bone is achieved at the fracture site. Morphological examination of bone biopsy samples from the implantation site of the plate and the plate itself with the deposited bioactive glass-based coating revealed active regeneration of bone tissue. This resulted in an increase in the density of the restored bone. According to the results of histological and morphometric examination it can be stated that deposition of a material containing bioactive glass on the contact surface of the metal plate promotes reparative osteogenesis at the site of bone damage and its morphogenesis of the lamellar type.
... Plasma-spray HA coatings have been used as surface coatings on metallic implants in orthopaedics since the mid-1980's (Geesink 1989, Furlong and Osborn 1991. The advantages that are sought in this application include (1) more rapid fixation and (2) increased and more uniform bone ingrowth and/or ongrowth at the bone-implant interface (Geesink 1988, Stephenson 1991, Cook 1992. ...
Reconstructing segmental bone defects after resection of malignant bone tumours is a long-standing clinical problem. With the increased knowledge of mesenchymal stem cells (MSCs), it may now be possible to reconstruct segmental bone defects using a tissue engineering approach. Treatment of bone tumours such as osteosarcoma involves chemotherapy. These chemotherapeutic agents are potent inhibitors of cell division and these drugs may affect regeneration of bone from osteoprogenitor cells. The ultimate aim of this study was to investigate the use of mesenchymal stem cells for repairing segmental bone defects after tumour resection. The effects of chemotherapeutic drugs on (1) differentiation of mesenchymal stem cells; (2) natural repair of bone defects; (3) regeneration and remodeling of the bones were studied. The in vitro effects of fibroblast growth factor-2 on mesenchymal stem cells were investigated and it was found that there was time and dose-dependent effects of fibroblast growth factor-2 on proliferation and chondrogenic differentiation but not osteogenic differentiation of mesenchymal stem cells. Secondly, the toxicity of chemotherapy agents on mesenchymal stem cells was demonstrated. Cisplatin and doxorubicin significantly inhibited proliferation and osteogenic differentiation of mesenchymal stem cell. Methotrexate did not inhibit proliferation if the cells were pre-treated with osteogenic supplements. The systemic influences of these chemotherapy agents on the adult as well as the immature rat skeleton were also quantitatively analysed. Ultimate bending (p=0.018 in adult rats and 0.061 in immature rats) and torsional strength (p=0.026 in adult rats and p=0.056 in immature rats) of the femur as well as the ultimate shear strength of the distal femur physis (p=0.044) was significantly reduced following chemotherapy. A significant reduction of cell numbers within the growth plate (p 0.001) and a change of growth plate morphology was evident. Using dual energy X-ray absorptiometry, radiography and histology it was demonstrated that bone regeneration was delayed in chemotherapy-treated rats in a femoral bone defect model. Finally, bone regeneration in normal and chemotherapy-treated rats was enhanced with mesenchymal stem cells and injectable fibrin glue scaffolds. It was shown that MSCs with fibrin glue could remain viable for up to 96 hours in tissue culture. When MSCs were used in conjunction with fibrin glue in vivo then the effects of chemotherapy could be alleviated and bone formation significantly enhanced. These studies demonstrated that the effect of systemic administration of chemotherapeutic agents on bone strength, regeneration and repair and indicated that a tissue engineering approach in patients undergoing chemotherapy may be beneficial for treating segmental bone defects after tumour resection.
... [60]. Столь высокий потенциал к остеоинтеграции позволяет преодолевать промежутки между имплантатом и костью до 2 мм, сглаживая погрешности хирургической техники [61]. В то же время важной проблемой ГА покрытия является деградация, которая может привести к расшатыванию имплантата [62]. ...
Background . Total hip arthroplasty is an effective type of surgery with excellent survival rates of modern implants. From the very beginning of the widespread introduction of total hip arthroplasty, the cement technique of components fixing prevailed. However, many researchers associated the development of osteolysis and the following loosening with the reaction to cement. The subsequent studies clarified the situation regarding the nature of osteolysis, but there remained the problem of insufficient stability of the cemented stems to withstand the penetration of polyethylene wear particles into the distal part of the stem with the development of loosening. An ideal endoprosthesis should ensure the normal hip biomechanics, joint painless functioning and improve the quality of life of the patient without the need for revision. The optimal results of cementless femoral stems functioning depend on the achievement of initial stability, osseointegration and equable transmission of tension onto the femur. There are many factors that influence osseointegration processes and the subsequent behavior of the implant. Understanding these factors is the key to choosing the optimal implant for a particular patient, taking into account the anatomical features of the femur.
The purpose of this article is to discuss upon the literature review the application of cementless femoral components, the possible causes of failure and its prevention from the point of view of the evidence-based practice.
Materials . The search was conducted in the PubMed, eLIBRARY databases and through the Web of Knowledge. Survival rates and prevalence of various implants in the structure of primary arthroplasty were estimated on the basis of annual reports of a number of national registries, as well as the hip arthroplasty registry of the Vreden National Medical Research Center of Traumatology and Orthopedics. Among the factors discussed are the properties of the components material, the form of the implants, surface properties, and the influence of the anatomical features of the femur. Additionally, the most used types of cementless femoral components were assessed.
Conclusion . Cementless femoral components demonstrated the excellent long-term survival and functional results. The currently prevailing type of the prosthesis intimate attachment to the bone is the biological fixation, especially in groups of young patients. Future studies of cementless implants should necessarily take into account the patient’s age, level of activity, type of bone canal, the presence of deformities, and the friction pair used. This will make it possible to draw clearer conclusions in what clinical situation it is advisable to use the femoral components of a particular design.
... Choudhuri et al. (2009) successfully deposited bioceramic coating (hydroxyapatite and titanium) for different applications of orthopedic implants and dental to enhance bone integration. Various researcher (Tsui et al., 1998, Sun et al., 2001, Stephenson et al., 1991 also used HAP coating (Ca10(PO4)6 (OH)2 for orthopedic implants and dental applications since HAP coating possesses similar crystallographic and chemical characteristics as that of bone mineral. Cinca et al. (2016) studied the deposition behaviour of bioactive HA cold sprayed coating on Ti6Al4V and Al7075T6 substrate. ...
Purpose
This paper aims to consolidate the results of various researchers focusing the different applications, so that this paper could become the torch bearer for the futuristic researchers working in the domain of cold gas dynamics spray coating.
Design/methodology/approach
A study on the cold spray coating is presented by summarizing the data present in literature. Important factors such as coating temperature, pressure, coating thickness, particle size, which affect the erosion-corrosion (E-C) resistance, physical and mechanical properties of boiler steel are stated. This paper also addresses the use of cold spray coating and compares it with other different thermal spray processes.
Findings
From the literature review, it was noticed that cold spray technology is best as compare to other thermal spray processes to reduce porosity, increase hardness, adhesion strength and retention in properties of feedstock powders.
Originality/value
Cold spray coating technology has a great potential in almost every field especially in restoration of surfaces, generation of complex surface, biomedical application, resist hot corrosion, wear, oxidation and erosion corrosion.
... 77 Ceramics have notable biocompatibility and structure similar to normal bone. 79 Approximately 60% of the commercially available bone graft substitutes for spinal reconstruction procedures are ceramics and include calcium sulfate, bioactive glass, and calcium phosphate. 80 Silicate-substituted calcium phosphate has great ease and versatility of use, yielding fusion rates of 90% throughout the cervical, thoracic, and lumbar spines. ...
As reconstructive needs often extend past the soft tissue alone, a plastic surgeon must also be well versed in the methods of bony reconstruction. Understanding of the basic science of fracture healing and the biochemical mechanisms of the different bone grafts, bone substitutes, and orthobiologics is essential to selecting among the many different options available to the modern plastic surgeon. This review provides a broad overview of these different options and the specific applications for plastic surgeons based on anatomic location.
... This feature of HAP may be of great importance for implant fixation. This formed layer for simulated body fluid has ensured the biocompatibility of the Ti coated layer [25]. ...
Abstract
TiO2 coatings were deposited on medical grade 316L stainless steel samples substrates by radio frequency (RF) sputtering technique. The influence of varying RF sputtering power (50- 150 W) on the corrosion rate and biocompatibility was investigated. The thickness of TiO2 coating was found to increase considerably in the range 245-910 nm while varying the power 50-150 W. The corrosion measurements showed a great improvement in corrosion characteristics for coated samples; i.e. a small corrosion rate of (9.09 ×10-4) mm/y for a coated sample at sputtering power 150 W compared with (2.419 ×10-2) mm/y for the uncoated sample. TiO2 coating stainless steel substrate at power 150 W was immersed in natural uniform hydroxyapatite which concentrates five times simulated body fluid (SBF×5) at various times. The optical microscope images observations revealed an increase of coating efficiency with increasing immersion time. This research demonstrates a new low-cost approach to produce high corrosion resistance biocompatible materials.
... findings suggest that the Furlong cup design can achieve long-term stability despite technical implantation defects. It has been histologically proven that the osteoconductive properties of the HA coating can close gaps of up to 5 mm between the implant and bone (27). This has been radiographically reflected in several clinical series (5,20). ...
We assess 254 consecutive primary total hip replacements (THRs) using a fully hydroxyapatite (HA)-coated stem and socket (Furlong; JRI, London, UK). Minimum follow-up was 10 years. Harris hip score (HHS) increased from 49.8 preoperatively to 86.2 at follow-up. The most remarkable clinical finding was the near absence of thigh pain. After 10 years of follow-up, all stems met stability criteria and none needed revision for aseptic loosening. Three cups (1.2%) were revised for aseptic loosening. Two more cups were revised for recidivant dislocation. Varus placement of the femoral stem was present in 63 hips (24.8%) and valgus in 13 hips (5%). None of these technical defects showed radiologic progression, and there was no measurable correlation between them and the clinical score. Intraoperative femoral fractures occurred in 25 cases (9.8%) with no further influence on implant evolution. These findings strongly support the use of the JRI Furlong system for primary THR because it provides excellent clinical and radiologic results, with 0% and 1.2% cup and stem aseptic loosening, respectively, at 10 years. In addition, its tolerance to technical implantation defects makes it suitable even for less experienced hip surgeons.
... Due to high temperature; poor cohesion and adhesion strength and particularly large amount of phase transformations were reported [37,38]. In addition, conversion of HAP into other calcium phosphate phases i.e. αor-β tricalcium phosphate, tetra calcium phosphates or calcium oxide and the crystallinity of HAP was also reported to be lowered [39,40]. These disadvantages can be overcome with an aid of new thermal spray process, known as cold spraying (CS). ...
Cold spraying has been effectively investigated for spraying of various metals, alloys and composites. Coating of ceramics like Hydroxyapatite (HAP) using thermal spraying has been investigated extensively, but there is a dearth of research related with HAP deposition using cold spraying. Many investigations have discussed theinfluential cold spraying parameters, but none has reported the relative percentage contribution of each of them. This paper examined the numerically investigated percentage contribution of five important factors of cold spraying viz. gas type, gas inlet pressure, gas inlet temperature, particle size and particle temperature on nozzle exit particle velocity from convergent-divergent (CD) nozzle. Simulated particle was given the properties of HAP powder. Optimum combination of levels and expected optimum exit particle velocity was analyzed through confirmation test and highest velocity was then mathematically validated and plotted using gas dynamic principles. Critical particle velocity for HAP deposition was also reported. Hence this research investigation throws light on the relative importance of cold spraying parameters using HAP powder and thus provides more insight into the behavior of HAP particle velocity for its successful deposition using cold spraying.
... The sol-gel reactions allow HAp to be processed into films and coatings on ceramic substrates [14][15][16]. A bioactive calcium phosphate coating can improve bonding between natural bone and a titanium or titanium alloy implant [17,18]. The association of type I collagen with minerals forms hybrid materials having unique properties depending on the nature and size of the mineral, its dispersion in the collagen scaffold and the orientation of the fibrils. ...
The aim of this study was to synthesize and characterize a hybrid composite based on type I hydrated collagen, hydroxyapatite and a silane precursor (amino-propyltriethoxysilane). Through sol-gel approach of the precursor and noncovalent immobilization of collagen on the surface of hydroxyapatite, a new type of hybrid material was obtained in which microspheres comprising silica and hydroxyapatite particles are dispersed in an oriented fibrous network of collagen fibrils. Moreover, the sol-gel reactions between the above-mentioned components were not accompanied by conformational changes of the adsorbed collagen, thus preserving its secondary structure.
... Like other bioactive materials, bioactive ceramics can directly bond to the living bone tissue. Sintered HA (hydroxyapatite) has been recorded a remarkable success as implant materials in the clinical use due to its bioactivity and osteoconductivity [4][5][6][7]. However, the low fracture toughness of HA ceramic limit the scope of clinical applications [8,9]. ...
... coatings for orthopaedic implants (Geesink, 1990;Geesink et al., 1988;Stephenson et al., 1991), maxillofacial surgery (Hench, 1998), scaffolds for bone growth (Hench, 1998), materials in total hip and knee surgery (Hench, 1998;Gatti et al., 1990;van Hemert et al., 2004) and as a drug release matrices (Ginebra et al., 2006;Paul and Sharma, 1999;Itokazu et al., 1998;Hamanishi et al., 1996). Calcium phosphates are widely available and are of interest to a variety of fields including geology, chemistry, biology and medicine (Dorozhkin, 2007). ...
... To summarize the available information on the biomedical and biomechanical properties of implants coated by CaPO 4 , one can claim the following. If compared to uncoated controls, deposited CaPO 4 were found to induce bone-to-implant contacts [574,818,819,[879][880][881][882][883][884][885][886][887][888][889][890], improve initial stability [891], implant fixation [763,[892][893][894][895][896] and nanomechanical properties of adjacent bones [897], show higher torque values [881,886,896,898] and push-out strength [899], seal the interface from wear particles [900], facilitate bridging of small gaps [901,902], reduce ion release from the metallic substrates [806,[903][904][905], slow down metal degradation and/or corrosion [38,42,72,73,414,791,[906][907][908], accelerate bone growth [909][910][911], remodeling [912,913] and osteointegration [35,437,480,767,[914][915][916][917], improve biocompatibility [918], induce osteoconductivity [846,[919][920][921][922], osteoinductivity [923] and osteogenesis [130,889,896,924,925], improve the early bone [437,895,[925][926][927] and healing [928] responses, prevent from formation of fibrous tissues (Fig. 33) [147,929], increase ectopic bone formation [459], osteoblast density [930] and their proliferation [669], as well as the clinical performance of orthopedic hip systems (see below). Furthermore, antibacterial properties of deposited CaPO 4 were detected in some studies [38,930]. ...
Since various interactions among cells, surrounding tissues and implanted biomaterials always occur at their interfaces, the surface properties of potential implants appear to be of paramount importance for the clinical success. In view of the fact that a limited amount of materials appear to be tolerated by living organisms, a special discipline called surface engineering was developed to initiate the desirable changes to the exterior properties of various materials but still maintaining their useful bulk performances. In 1975, this approach resulted in the introduction of a special class of artificial bone grafts, composed of various mechanically stable (consequently, suitable for load bearing applications) implantable biomaterials and/or bio-devices covered by calcium orthophosphates (CaPO4) to both improve biocompatibility and provide an adequate bonding to the adjacent bones. Over 5000 publications on this topic were published since then. Therefore, a thorough analysis of the available literature has been performed and about 50 (this number is doubled, if all possible modifications are counted) deposition techniques of CaPO4 have been revealed, systematized and described. These CaPO4 deposits (coatings, films and layers) used to improve the surface properties of various types of artificial implants are the topic of this review.
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... To this end, a novel femoral stem was designed to allow for easier removal without compromising retention properties [6]. The stem was coated with hydroxyapatite, which promotes bone ingrowth and bridges bone/implant gaps [7][8][9]. For evaluation in a weightbearing model, the stem was implanted in goats. ...
The increasing incidence of prosthesis revision surgery in the Western world has led to an increased focus on the capacity for stem removal. We previously reported on a femoral stem implanted in goats with an approximate 15% reduction in retention force by drilling longitudinally orientated grooves on the side of the stem. In this current study, we aimed to histologically evaluate the bony apposition towards this stem and correlate this apposition with the pullout force.
We analyzed the femora of 22 goats after stem removal. All stems remained in place for 6 months, and the goats were allowed regular loading of the hip during this time. For histological evaluation, all femora were immersed in EDTA and decalcified until sufficiently soft for standard technique preparation. We evaluated bone apposition, the presence of foreign particle debris and other factors. The apposition was evaluated with a scoring system based on semi-quantitative bone apposition in four quadrants. Kappa statistics were calculated for the score. We correlated the retention force with the amount of bone apposition.
The stem drilling was the only significant factor influencing the retention force (p = 0.020). The bone apposition Kappa score comparing poor and good apposition scores was fair (κ = 0.4, 95% CI 0.00-0.88). Signs of foreign body reaction were noted in 5 of 22 goats.
Based on the current findings in an experimental goat model, it appears that the effect of drilling tissue/bone out of the longitudinal grooves has a more significant impact on the retention force required to remove the stem than the amount of bone apposition outside the stem grooves. This observation may be further explored in the research of stem designs that are potentially easier to remove.
... It appears that hydroxyapatite enhances ingrowth in both stable and unstable conditions [27,28], whereas calcium phosphate coating is mainly studied with stable implants. The results of the present study support the view that the calcium phosphate coating requires a stable fixation to obtain osteointegration in a loaded situation, compared with hydroxyapatite. ...
Background
Since the introduction of uncemented hip implants, there has been a search for the best surface coating to enhance bone apposition in order to improve retention. The surface coating of the different stems varies between products. The aim was to assess the retention force and bone adaption in two differently coated stems in a weight-bearing goat model.Materials and methodsHydroxyapatite (HA) and electrochemically deposited calcium phosphate (CP; Bonit®) on geometrically comparable titanium-based femoral stems were implanted into 12 (CP group) and 35 (HA group) goats. The animal model included physiological loading of the implants for 6 months. The pull-out force of the stems was measured, and bone apposition was microscopically evaluated.ResultsAfter exclusion criteria were applied, the number of available goats was 4 in the CP group and 11 in the HA group. The CP-coated stems had significantly lower retention forces compared with the HA-coated ones after 6 months (CP median 47 N, HA median 1,696 N, p¿=¿0.003). Bone sections revealed a lower degree of bone apposition in the CP-coated stems, with more connective tissue in the bone/implant interface compared with the HA group.Conclusion
In this study, HA had better bone apposition and needed greater pull-out force in loaded implants. The application of CP on the loaded titanium surface to enhance the apposition of bone is questioned.
... One approach involves the deposition of calcium phosphate coatings, which are described to induce an increased bone-toimplant contact, 4 to improve the implant fixation, 5 and to facilitate the bridging of small gaps between implant and surrounding bone. 6 Biomimetic methods have been developed to deposit such coatings at room or body temperature from low concentration calcifying solutions onto pretreated titanium surfaces. 7−9 It has been shown that it is possible to coprecipitate organic macromolecules, such as proteins 8 and antibiotics 9 with the deposited calcium phosphate coatings. ...
The preparation of organic-inorganic composite coatings with the purpose to increase the bioactivity of bioinert metal implants was investigated. As substrates glass plates and rough titanium surfaces were employed. The method comprises the deposition of polyelectrolyte multilayers (PEMLs) followed by immersion of the coated substrate into a calcifying solution of low supersaturation (MCS). Single or mixed PEMLs were constructed from poly-L-lysine (PLL) alternating with poly-L-glutamate, poly-L-aspartate and/or chondroitin sulfate. The PEML coatings had a grainy topography with aggregate sizes and size distributions in correlation with the ß-sheet content of the PEML assembly. The induction time, τ, preceding the onset of calcium phosphate crystallization decreased with decreasing aggregate sizes, i.e. with increasing order of the organic matrix. In contrast, the crystal morphology and structure were dependent on the pH and supersaturation of MCS, rather than on the composition of the substrate coating. Crystals grown on both uncoated and coated substrates were mostly platelets of calcium deficient carbonate apatite, with the Ca/P ratio depending on the precipitation conditions.
This thesis covers a range of different biomechanical aspects related to short- and long-term implant fixation of tibial and femoral components in TKA, using a variety of research methods: experimental testing, literature review, and computational modeling
This retrospective study of 1149 of cemented intra-medullary stemmed Stanmore bone tumour lower limb massive endo-prostheses, identified that aseptic loosening was the most common form of implant related failure. Revision for aseptic loosening occurred in 14.5% of the 1149 cases. The probability of surviving aseptic loosening for 10 year for proximal femoral, distal femoral and proximal tibial replacements was 87.9%, 65.1% and 51.5% respectively. Patients at greatest risk of loosening were young patients with a distal femoral or proximal tibial replacement, or patients with extensive resections of the distal femur or proximal tibia. Those patients with short proximal femoral resections were at greater risk than those with extensive resections. Clinical and radiographic evaluations of patients were poor predictors of loosening. However, there was a correlation between pain and radiographic radiolucent lines. This study provided impetus to develop three new method of improving implant fixation. These were - 1. enhanced fixation of cemented intra-medullary stemmed replacements using porous beaded collars or hydroxyapatite coated collars. Bony bridging did not occur with porous collared replacements but did with 81.8% of hydroxyapatite coated replacements. 2. uncemented intra-medullary fixation using press-fit, hydroxyapatite coated custom-made stems. After laboratory and cadaveric studies, a clinical trial of 20 patients was undertaken. Early radiographic results of target groups were encouraging. 3. extra-cortical fixation using hydroxyapatite coated extra-cortical plates. Inspired by the first Stanmore replacements, extra-cortical plated fixation was investigated using a goat model. Histological results of mid-shaft tibial replacements identified osseointegrated encompassed plates. The success of the animal model, led to the insertion of an extra-cortical plated distal femoral endo-prosthesis. All three methods of improving the fixation showed encouraging results. The acceptance and increasing use of enhanced methods of fixation has reinforced the value of this work.
The Authors analyse the cases treated with cementless hip endo- and arthroprostheses from 1983 to the present at the Orthopaedic and Traumatology Department of the University of Siena, Italy.
They review, in chronological order, the cases treated with three different types of cementless hip prosthesis: the GCO, the PCA and the Omnifit prosthesis.
Cellulose nanofibrils is one of the future potential giants in the medical implant industry. Its unique properties make it the ideal material for use in both permanent prosthetic devices and non- permanent implants such as screws and plates. To increase the usability of this material, the addition of super paramagnetic iron oxide nanoparticles is needed to gain MRI and X-Ray visibility. The methodology for how to homogeneously integrate these particles into the system using the addition of coating agents is explored. This research demonstrates that the addition of coating agents to the iron oxide nanoparticles can affect both the pH flocculation behavior and the adhesion of the particles to fibrils. In addition, the research finds that the addition of coating agents affects the physical characteristics of the fibrils themselves.
We have reviewed 83 consecutive cementless Furlong hydroxyapatite (HA)-coated threaded acetabular components which were inserted in 75 patients. The mean age of the patients at the operation was 54 years (range 31 to 67 years) and the mean follow-up period was 61 months (range 40 to 82 months). Large size gaps at the implant -bone interface (attributed to failure to achieve bone-prosthesis contact), were present in 89% of the cases on the initial radiographs. At the last follow-up, the gaps were either no longer visible or had decreased in 95% of the cases. Radiolucencies were absent in well-fixed components. Three acetabular components were considered to be loose and are awaiting revision, giving a 3.6% aseptic loosening rate. The remainder of the cups were radiographically stable with positive evidence of bone ingrowth and no signs of impending loosening.
Background:
Cement fixation of total knee components remains the gold standard despite resurgence in cementless fixation with the goal of long-term durable fixation. Initial stability is paramount to achieve bony ingrowth of cementless components.
Methods:
Twelve cemented and cementless tibial baseplates were implanted into sawbones and tested using a physiological medial-lateral load distribution for 10,000 cycles to represent 8 weeks of in vivo function. Micromotion was measured at 5 locations around the baseplate during loading.
Results:
Cycling had a significant effect on the change in micromotion between maximum and minimum loads at the anterior, medial, lateral, posteromedial, and posterolateral tray edge locations. A significant effect of fixation technique was detected for the anterior (P < .001), medial (P = .002), and lateral (P = .0056) locations but not for the posteromedial (P = .36) or posterolateral (P = .82) locations. Differences in micromotion between cemented and cementless components did not exceed 150 μm at any tested location.
Conclusion:
The micromotion experienced by cementless tibial components in the present study may indicate a lower initial mechanical stability than the cemented group. However, this difference in initial stability may be subclinical because the differences between average cemented and cementless micromotion were <150 μm at all measured locations under the loading regime implemented.
### History of the Use of Hydroxyapatite in Orthopaedics
The term apatite was first applied to minerals by Werner45, in 1788. It now denotes a family of crystals with the formula M10(RO4)6X2, where M is usually calcium, R is usually phosphorus, and X is hydroxide or a halogen such as fluorine. The relationship to bone mineral was first suggested by Proust and Klaproth45, also in 1788. Only after the development and use of x-ray diffraction did Dejong confirm, in 1926, that the inorganic phase of bone was an apatite49. Bone mineral was found to be quite complex and included various types of hydrated calcium phosphates, the most common being calcium hydroxyapatite (Ca10[PO4]6[OH]2).
To the best of our knowledge, the earliest use of calcium-phosphate materials in humans was as a powder of varying crystalline composition to improve bone-healing. Albee and Morrison, in 1920, reported accelerated formation of callus3, but others later observed no major advantage with use of the hydroxyapatite powder80,147. As a bulk implant, calcium-phosphate materials were first used for dental applications133, as reported in 1971. More recent reports in the dental literature have attested to the success of bulk calcium-phosphate materials composed of pure hydroxyapatite and used as a bone-graft substitute12,35,57,68,135,137. Patients who had hydroxyapatite grafts were followed for a maximum of seven years57 and were evaluated clinically12,35,57,137, radiographically12,35,57, and with computer-assisted densitometry68. In two studies135,137, biopsy specimens were obtained for histological analysis. In addition to impressive evidence of osseointegration, no adverse effects of hydroxyapatite …
Introduction:
Total hip replacement is a successful procedure with long survival records compared to other joint arthroplasties. Cemented implants have been available for many years, however the complications associated with loosening and, ultimately, failure over time has led to the development of cementless stems and implants.The ideal prosthesis should recreate a biomechanically normal hip joint, allow pain-free function and last the patient's life span without requiring revision. Optimal results with uncemented femoral stems rely on obtaining initial stability, osseointegration, biological fixation, and uniform stress transfer to the proximal bone.There are a multitude of factors that can affect the integration, stability and fixation of these stems into bone, and understanding these factors is the key to choosing the appropriate implant for a specific femur.
Methods:
This article aims to discuss cementless prostheses based on evidence-based practice. Geometry, roughness, stem coating, technique and bone quality are among the factors discussed. This was achieved through a review of the current literature.
Conclusions:
Uncemented femoral stems have shown good, long-term survivorship and functional outcome, with promising results in younger patients.Limitations in the current literature make it difficult to assess and compare different designs to determine optimal indications for each type.Biological fixation, in which the prosthesis is directly fixed to the bone, is the preferred fixation method.Future studies of cementless implants should consistently address patient age, activity level, bone type, and deformities so that more definitive conclusions can be drawn about when to use each design.
Metallic implant materials used in load-bearing applications are inert in nature in their native state. The surface properties of the material and its interaction with the surrounding physiological fluid determine the success of the biomedical implant. In this regard, bioactive nanostructured coatings are being recognised as potential approach to enhance the biological and corrosion properties of the conventional inert materials. In this review, recent advances in biomedical applications of nanostructured hydroxyapatite coatings on stainless steel implant materials are highlighted with special focus on the electrochemical deposition of hydroxyapatite and their consequent biological activity. Furthermore, osteoblasts functions and cellular activity on the nanostructured hydroxyapatite coatings processed by other techniques is also discussed. The potential application of such next generation materials as biomedical implants is also addressed.
Young active patients will usually outlive the fixation of a total hip or knee arthroplasty. There is widespread concern about the considerable risk of failure in these patients, especially because of the subsequent need for even more difficult operative treatment with fewer beneficial results (1–4). As a result, there is an increased interest in other principles for implant fixation, such as biological fixation to the bone without the use of bone cement (5).
The use of hydroxyapatite-coated prosthesis for total hip arthroplasty began in 1985 and has gained favor with reports of prompt biological fixation and clinical success. The quality and quantity of the coating is sensitive to application techniques, metal substrate, and manufacturing controls—all important in creating a clinically successful coating. Bioactive coatings other than hydroxyapatite have had mixed success and are generally not available for clinical use at this time. Clinical experience with hydroxyapatite-coated hip implants have focused on the femoral component, where results approach the standard of cemented components. Acetabular components have been less impressive when hydroxyapatite is the primary source of fixation without macrostructured substrate or augmentation with screws. Analysis of sequential follow-up radiographs in patients with hydroxyapatite-coated hips consistently reveals the changes associated with prompt and tenacious biologic fixation of the femoral component. These changes are apparent at 6 months and persist beyond 8 years. While the optimal design of the components, the surface structure of the metal substrate, and the ideal application method are still evolving, the use of hydroxyapatite-coated prostheses for hip arthroplasty has been proven safe and successful for clinical use where biologically fixed components are indicated.
To overcome the problems in cemented arthroplasty and obtain reliable permanent fixation in the absence of cement, several types of cementless prosthesis have been developed. The uncoated, press-fit, cementless stem for total hip arthroplasty (THA) used in young age groups frequently result in marked subsidence and loosening around ten years postoperatively, even with the most precise surgical techniques. The porous, full-coated, cementless stem was then developed in an attempt to encourage bony ingrowth into the pores, thus aiming at firm mechanical anchoring between the stem and the femur. This prosthesis model, however, provoked bone absorption along the stem presumably due to the stress-shielding effect on the femur.
Charnley’s introduction of bone cement to hip arthroplasty in 1960 [12] made it possible for the procedure to be carried out worldwide to the extent it is today. With increasing numbers of procedures and increasing implantation time, however, the numbers of failures have also increased. The principal cause of failure is aseptic loosening of the implant [40]. Somewhat too prematurely, bone cement was considered responsible, causing a trend for direct (or biological) cementless implantation to develop worldwide. At the same time attempts were being made to improve the cement and, in particular, the cementing technique.
Metallic biomaterials currently in use for load-bearing orthopedic applications are bioinert. Recent in vitro and in vivo studies demonstrated that Ta is a promising metal that is bioactive, but its applications have been limited by processing challenges. We report how to process Ta to create net shape porous and dense structures as well as coatings using Laser Engineered Net Shaping (LENS). Porous Ta samples with relative porosities between 60 to 90% have been successfully fabricated and characterized. In vitro cell materials interactions, using human osteoblast cell line showed six times better biocompatibity than Ti. In vivo results in a rat distal femur defect model shows that bone tissue integrated within 8 weeks of implantation and increasing porosity helped tissue integration. Our results demonstrate that Ta can be processed using LENS™ based agile manufacturing technology both in coating and porous metal form.
This chapter reviews basic bone biology and bone graft technology to give an insight into the increasingly biomimetic approach being pursued in this field. Many current synthetic bone graft substitute materials have calcium phosphate chemistries reflecting the composition of bone mineral, and hierarchical pore structures similar to cancellous bone. Significant research effort has been devoted to understanding how slight variations in chemistry and pore structure impact a graft material's ability to support or stimulate bone healing. It appears that the best results are obtained when a graft chemistry or structure is designed to mimic the natural tissue.
As dominant materials used in today's joint prostheses, titanium and cobalt-chromium alloys frequently suffer from failure due to wear particles, mismatch of modulus, lack of sufficient osseointegration for cementless implants, etc. From this point of view, this chapter will first review material science fundamentals of titanium and cobalt-chromium alloys currently used in hip and knee replacement as well as pointing out their shortcomings in some specific areas. Then, advances in this field will be discussed. Lastly, this chapter will focus on discussing one of the promising metal surface modification methods, called anodization, which has increased implant osseointegration. Some additional surface treatments to increase wear resistance and biocompatibility of titanium and cobalt-chromium alloys surfaces will also be discussed at the end of the chapter.
This chapter provides an overview of orthopedic research using animal models, with emphasis on approaches that have dominated the field for the past 5–10 years. Some of the most successful orthopedic procedures, such as joint replacement, tendon healing, fracture treatment, use of biomaterials, and osteoporosis, to name a few, have relied heavily on animal experiments. There are, however, many orthopedic problems in humans that have not been solved because only relatively advanced stages of the disease can be studied and no proper control group is available. Furthermore, the basic mechanisms of some diseases are still unknown because of lack of animal models. Tissue engineering and gene therapy in orthopedics are rapidly emerging as individual disciplines, and the use of animal models will be essential before human clinical trials can be initiated. Orthopedic surgeons interested in pursuing an idea or hypothesis must first consider the appropriate animal model and understand interspecies differences. This means acquiring sound knowledge not only of the anatomy, biology (including response to different anesthetics and analgesics), biomechanics, and physiology of the various animals, but their general husbandry requirements, including appropriate nutrition and housing, as well.
Die Einführung des Knochenzementes in die Hüftarthroplastik durch John Charnley [12] hat deren Entwicklung erst in dem Maß ermöglicht, wie sie heute weltweit durchgeführt wird. Mit zunehmender Verbreitung und zunehmender Implantationszeit stieg aber auch die Versagerquote an. Hauptursache für den Mißerfolg ist die aseptische Lockerung des Implantates [41]. Etwas voreilig wurde für diese der Knochenzement verantwortlich gemacht, weshalb in den 70er Jahren weltweit ein Trend zur direkten, auch biologisch genannten, zementfreien Fixation der Implantate einsetzte. Gleichzeitig wurden Anstrengungen unternommen, den Knochenzement, v. a. die Zementiertechnik, zu verbessern.
Various conventional spray techniques have been exploited for more than two decades to coat bio-ceramics such as Hydroxyapatite (HAP) and its composites on metallic substrates for biomedical applications besides many limitations viz. residual stresses, evaporation, phase alterations and debonding etc. Cold spray technology overcome number of traditional thermal spray shortcomings and has been studied for engineering metallic materials. Deposition of HAP and its composites using cold spraying is still unexploited and holds tremendous potential in dental and orthopedic implant applications. This review will enumerate the research works and other crucial aspects of HAP deposition using thermal spraying. Present R&D efforts of cold spraying will be discussed and compared with the conventional spraying techniques. Studies and their conclusions related with synthesis, characterization, electrochemical evaluation and other valuable information of HAP will be extensively focused. In light of relative merits and demerits, research gap of using cold spraying for HAP deposition will be proposed and concluded.
The shear and tensile strength of a hydroxyapatite (HA) coating on a femoral component was studied after physiological loading conditions in 8 German Shepherds. A proximal macrostructure on the stem was used to protect this region from shear stresses. Another four implantations with uncoated components were used as controls. In vitro testing of the HA layer demonstrated excellent tensile strength and stability to surface deformation. The loaded implants were tested at 6, 12, and 24 weeks. At 6 weeks the HA-coated components could easily be removed by axial loading, whereas the HA layer remained undamaged on the metal. However, pull out tests of implants older than 12 weeks showed complete debonding of the HA layer from the non-macrostructured surface due to shear forces in all cases. Debonding of the HA layer was also observed with microradiography. The macrostructured surface prevented dislodging of the component from this area at pull out test by distributing shear forces. Unlike in uncoated implants, considerable amounts of bone remained attached onto the HA macrostructure when the surrounding femur was pulled out. Shear forces cause debonding of the HA layer, while tensile stress affects failure within the bone. Physiological loading partially produces gaps at the interface so direct transmission of tensile forces onto the bone is lost, and the coating-metal interface becomes the weak point in the system.
The interface mechanical characteristics and histology of commercially pure (CP) titanium- and hydroxyapatite- (HA) coated Ti-6Al-4V alloy were investigated. Interface shear strength was determined using a transcortical push-out model in dogs after periods of three, five, six, ten, and 32 weeks. Undecalcified histologic techniques with implants in situ were used to interpret differences in mechanical response. The HA-coated titanium alloy implants developed five to seven times the mean interface strength of the uncoated, beadblasted CP titanium implants. The mean values for interface shear strength increased up to 7.27 megaPascals (MPa) for the HA-coated implants after ten weeks of implantation, and the maximum mean value of interface shear strength for the uncoated CP titanium implants was 1.54 MPa. For both implant types there was a slight decrease in mean shear strength from the maximum value to that obtained after the longest implantation period (32 weeks). Histologic evaluations in all cases revealed mineralization of interface bone directly onto the HA-coated implant surface, with no fibrous tissue layer interposed between the bone and HA visible at the light microscopic level. The uncoated titanium implants had projections of bone to the implant surface with apparent direct bone-implant apposition observed in some locations. Measurements of the HA coating material made from histologic sections showed no evidence of significant HA resorption in vivo after periods of up to 32 weeks.
Of the first 300 consecutive patients who had a Charnley total hip replacement at the Mayo Clinic during the years 1960 to 1970, 207 (231 hips) were re-evaluated ten years postoperative by questionnaire and roentgenograms. Forty-three of these were also evaluated by personal examination. Roentgenographic loosening of the acetabular component was determined using the criterion of a complete radiolucent line more than one millimeter in width at the bone-cement interface or any migration or tilting of the component. For the femoral component, the criterion for loosening was a radiolucent line more than one millimeter wide at either the bone-cement or the cement-prosthesis interface, or any change in the position of the component. As previously reported, the incidence of loose components at five years was 6.5 per cent for the acetabular component and 24 per cent for the femoral component. At ten years the incidence of loosening had increased to 11.3 per cent for the acetabular component and 29.9 per cent for the femoral component. Therefore, between five and ten years postoperatively the rate of femoral loosening decreased, while the rate of acetabular loosening remained about the same. The overall-revision rate for loosening of total hip components increased from 3 per cent at five years to 7.4 per cent at ten years. Acetabular wear was not a significant problem. Resorption of the medial femoral cortex near the calcar was generally non-progressive and was not significantly related to loosening. two modes of loosening are suggested, the more common being cracking of the cement mantle due to circumferential (hoop) stresses within the cement. This series probably represents a so-called worst-case experience, since changes in design and materials as well as the improvements in surgical technique that have evolved over the past decade should provide significantly better long-term fixation.
Hydroxylapatite (HA)-coated and uncoated Ti-6A1-4V alloy femoral endoprostheses were evaluated in adult dogs. The femoral stems had proximal anterior, posterior, and medial pockets of either a commercially pure titanium porous coating or a grooved macrotexture. They also had a medial collar, with an inferior surface pocket of either the porous coating or the grooved macrotexture. HA-coated and uncoated specimens of each type were evaluated. The devices were placed as unilateral hemiarthroplasties in 12 dogs and remained in function for up to 52 weeks. Histologic sections from the uncoated grooved implants showed no direct bone-implant apposition in the proximal regions after up to 10 weeks; the HA-coated grooved implants demonstrated extensive direct bone-coating apposition after 5 weeks. Sections from uncoated porous implants evaluated after 10 weeks demonstrated approximately equivalent ingrowth to those sections from the HA-coated devices after 6 weeks. All HA-coated implants demonstrated consistent bone-implant apposition with no fibrous tissue interposition. The HA-coated surfaces were associated with increased bone deposition and proliferation at early implantation periods. In no histologic section examined was there any evidence of deterioration of the HA coating, nor was any separation of the coating from the substrate material observed.
Ein nach 7wöchiger In-situ-Zeit explantierter Femurschaft einer Hydroxylapatitkeramik-beschichteten IRI-Furlong-Hüftendoprothese aus TiA 16 V4 wurde anhand nicht-entkalkter Dünnschliffe vorläufig licht- und rasterelektronenmikroskopisch untersucht. Die intakte Hydroxylapatitkeramik-Beschichtung (Osprovit) ist fast ausnahmslos von neugebildetem Knochen bedeckt, der den Reifegrad und Mineralgehalt jungen Lamellenknochens aufweist. Der obligat vom Insertionstrauma herrührende Spalt zwischen Prothese und Femur wird offensichtlich durch bilaterale Osteogenese, d.h. durch eine primär sowohl auf der endostalen Knochenfläche als auch auf der Hydroxylapatitkeramik ablaufende Knochenneubildung, überbrückt. Dieser neugebildete Knochen ist substantiell mit der Hydroxylapatitkeramik verwachsen, so daß an keiner Stelle der Grenzzone Bindegewebe existiert. Durch diese im kortikalen wie im spongiösen Lager abgelaufene Verbundosteogenese entsteht - im Gegensatz zum bisher erreichbaren Formschluß - zwischen Implantat und Knochen eine kraftschlüssige Verbindung. Dieses mit Hilfe der Hydroxylapatitkeramik-Beschichtung erstmalig realisierte Ergebnis bedingt unausweichlich, das Konzept der Prothesenverankerung im Knochen biomechanisch grundsätzlich neu zu formulieren.
A review of 333 consecutive Charnley total hip arthroplasties four to seven years after operation showed that twenty-eight patients had died, and three deaths were directly related to the surgery. The survivors had an average improvement of 46.6 points in their evaluation scores to a level of 91.3 points. Four deep infections occurred for which removal of the prosthesis was required. Thirteen hips dislocated postoperatively, and five of them required additional surgery. Three were four sciatic-nerve injuries and all but one resolved. Wear of the acetabular component was evident in seventeen hips, measuring two millimeters in six and one millimeter in eleven. With the marking system used, accurate measurement of wear was not possible. Roentgenographic evidence of loosening of the femoral component was found in 24 per cent of the hips, atributable more often to the quality of cement fixation than to the position of the components (varus-valgus). Varus loosening of two millimeters or more was associated with lower evaluation scores.
This study examines the biodegradation behaviour of calcium phosphate macroporous bioceramics consisting of hydroxylapatite or beta-whitlockite implants. The implantations were performed in hard tissue of femora and muscular tissue of dogs for periods of 6 and 12 month. With microradiography and light microscopy, respectively, of ground and thin sections it was shown that hydroxylapatite remained unchanged and beta-whitlockite degraded within 6 month in bone tissue. In the muscular tissue, the biodegradation of beta-whitlockite was slower. In addition, beta-whitlockite gave rise to a cellular response of lymphocytes and plasma cells rather than hydroxylapatite in the soft tissue region. For tissue response hydroxylapatite is more suitable as an implant material than beta-whitlockite.
The biologic attachment characteristics of hydroxyapatite (HA)-coated porous titanium and uncoated porous titanium implants were investigated. The implants were placed transcortically in the femora of adult mongrel dogs and evaluated after periods of three, six, and 12 weeks. The HA coating was applied using a modified plasma spray process to samples with pore volume and pore size of the porous coating expanded to equal the pore morphology of uncoated porous specimens. Mechanical push-out testing revealed that the bone-porous material interface shear strength increased with time in situ for both the uncoated and HA-coated implants. The use of the HA coating on porous titanium, however, did not significantly increase attachment strength. Histologic and microradiographic sections yielded similar qualitative results in the amount of bone grown into each system. After three weeks, both systems displayed primarily woven bone occupying approximately 50% of the available porous structure. Six and 12 weeks postimplantation, each system displayed more extensive bone ingrowth, organization, and mineralization, with only limited areas of immature bone. Histologically, differences were noted at the ingrown bone-porous material interface between the two implant types. The HA coating supported mineralization directly onto its surface, and a thin osseous layer was found lining all HA-coated surfaces. An extremely thin fibrous layer was observed separating the uncoated titanium particle surface from ingrown bone. There was no extensive direct apposition or lining of the ingrown bone to the uncoated porous titanium particle surfaces.
In rabbits and goats, test implants with a porous surface of two layers of Tl-6A;-4V beads were examined at intervals for bond strength with bone. Half of the implants were coated with hydroxyapatite by plasma spray. The bonding strength with bone in the coated specimens was about four times greater than that of the uncoated specimens at two weeks, and twice as strong at six weeks. Twelve weeks after implantation, the strengths were similar. The hydroxyapatite coating of the beads provided earlier and stronger fixation.
A mechanical and histological evaluation of uncoated and hydroxylapatite-coated titanium implant materials was performed in this study. Mechanical push-out testing results indicated that the hydroxylapatite-coated implants exhibited significantly greater values of maximum interface shear strength and interface shear stiffness than the uncoated implants. Hydroxylapatite-coated implants demonstrated mineralization of bone directly onto the hydroxylapatite surface. The uncoated CP titanium implants showed a predominantly fibrous tissue interface, with only isolated instances of direct implant-bone apposition. An appropriate surface macrotexture, such as the one investigated, may be required to prevent the hydroxylapatite coating from being pulled off of the substrate by applied loads. The use of hydroxylapatite coatings can significantly enhance implant fixation by direct bone ingrowth or apposition by providing a mechanism for establishing considerable attachment strength shortly after implantation.
Total hip replacement using porous-coated cobalt-chrome femoral implants designed for biological fixation has been evaluated in 307 patients after two years and in 89 patients after five years. Histological study of 11 retrieved specimens showed bone ingrowth in nine and fibrous tissue fixation in two. Fixation by bone ingrowth occurred in 93% of the cases in which a press fit of the stem at the isthmus was achieved, but in only 69% of those without a press fit. The clinical results at two years were excellent. The incidence of pain and limp was much lower when there was either a press fit of the stem or radiographic evidence of bone ingrowth. Factors such as age, sex, and the disease process did not influence the clinical results. Most cases showed only slight resorptive remodelling of the upper femur, but in a few cases with a larger, more rigid stem, more extensive bone loss occurred. The results after five years showed no deterioration with time. Fixation by the ingrowth of bone or of fibrous tissue both appeared to be stable, but bone ingrowth gave better clinical results.
Permanent and bioresorbable hard tissue implant materials composed of calcium phosphate ceramics are currently under extensive investigation. In addition to being unusually well-tolerated, both porous and dense forms of these materials have demonstrated the ability to become chemically bonded to bone via natural-appearing bone cementing mechanisms. The results of animal and clinical studies indicate that these materials may find use as bone graft substitutes or extenders.
One hundred consecutive Müller curved-stem total hip replacements were reviewed ten years after operation. Twenty patients with twenty-two arthroplasties had died within the ten-year period without having a revision, and twenty-five arthroplasties had been revised for various reasons. Of the remaining fifty-three arthroplasties, thirty-five were classified as good or excellent, with Harris hip scores of 80 points or higher, and eighteen were classified as poor or fair, with scores lower than 80 points. Follow-up radiographs, made for all but six of the fifty-three hips at ten years, showed a 23 per cent incidence of migration of the acetabular component and a 28 per cent incidence of migration of the femoral component. In addition, there was a 15 per cent incidence of bone resorption in the proximal end of the femur without migration of the femoral component and a 4 per cent incidence of osteolytic defects about the femoral component, also without migration. Combining the radiographically loose replacement (migration) with the clinically loose ones (revised), the over-all incidence of aseptic loosening was 29 per cent for the acetabular component and 40 per cent for the femoral component. There was a positive correlation between the incidence of loosening of the femoral component and younger age, heavier weight, male sex, unilateral hip disease, a wide femoral canal, and varus position of the femoral component, whereas the incidence of loosening of the acetabular component was increased only in association with older age. The rate of loosening of the femoral component appeared to be higher during the early follow-up period and to decrease with time, while the rate of loosening of the acetabular component appeared to be lower during the early follow-up period but to increase with time.
Total hip arthroplasty: A review of three hundred and thirty-three cases with
- Beckenbaugh Rd
- Ilstrup
- Dm
Beckenbaugh RD, Ilstrup DM: Total hip arthroplasty: A review of three hundred and thirty-three cases with
Total hip arthroplasty: A review of three hundred and thirty-three cases with long term follow-up
- Beckenbaugh
Hydroxyapatite coated hip implants
- Geesink
The biological behaviour of the hydroxyapatite ceramic coating on a titanium stem of a hip prosthesis—the first histological evaluation of human autopsy specimens
- Osborn